1. Field of the Invention
This invention relates to a servo amplifier for a television camera lens, and more particularly to an electric circuit for controlling a servo-mechanism in a television camera lens for operating an automatic iris control mechanism, a zooming mechanism and a focusing mechanism. The present invention is particularly concerned with an improvement in the circuit for preventing a voltage drop in the circuit caused by an abnormal current flow occurring at the time of starting of a servomotor and the like.
2. Description of the Prior Art
In the conventional television camera which is used in a television studio equipped with a large power source equipment or outdoor with a power source car, it is possible to use a power source having a great capacity. Therefore, there is no fear of voltage drop when the servomotor is started or the rotation of the servomotor is inverted which causes a rush current to flow through the circuit of the camera.
In a handy type camera, however, which is compact in size and usually used without a large power source, the voltage drop caused by the rush current when the servomotor is started or the direction of rotation of the motor is inverted is of a significant problem. The rush current is a very abnormal current which suddenly rises up to five to six times as high as the normal current. By this suddenly flowing current, the source voltage of the battery or the terminal voltage of the constant voltage power source of the circuit is markedly lowered, which affects the operation of the video circuit or servomotor control circuit in the camera.